This invention relates to a simulator which issues signals simulating various plant conditions to control units of various installations. More particularly, this invention relates to a simulator for issuing various types of signals simulating actual steel rolling to a control unit, for example, when the steel material is not actually being supplied, in order to check the controllability of the control unit and train operators.
FIG. 1 shows a typical block diagram of a conventional simulator. For example, a simulator of this type includes a controller 1 for controlling a hot strip mill which provides input signals simulating whether or not a roll material is supplied and how fast it is fed, and the simulator 2 delivers a conditioned process input signal D.sub.p through, for example, relay logic 3 illustrated in FIG. 2, for the controller 1. In this type of simulator, a process input signal Pv is input to the controller 1 for plant control through relay logic 3. In other words, the relay logic 3 in FIG. 2 yields an input signal ei to the controller 1 based on the logical switching of an actual process input signal Pv and the simulating signal D.sub.p, by means of a simulating mode signal Ms(FIG. 2) which is applied to an input terminal of the gate circuit 31 and instructs whether or not the simulator is operated. The controller 1 performs necessary operations (for instance, a PID control operation) according to the input signal ei and outputs a control signal Po that can trigger the actual process. This control signal Po is fed back to the input terminal of the simulator 2.
The conventional simulator provides disadvantages in that the larger the plant system, the larger the feed back input to the simulator 2, and in that relay logic is required for the input to each controller 1. This makes the system complicated and requires a large scale amendment upon a change of the simulation logic. When the relay logic is composed of switches, the logic is easily modified, but there is a problem such as a time lag because the input to the controller 1 is made by means of the switches.